Pipe Inspection System Research Articles

Gauging and Imaging of Pipes using Water-Immersible Ultrasonic Instrumentation System

Abstract The purpose of this research work is to establish the functionality of the novel ultrasonic non-destructive inspection system and accurate gauging of pipes and to locate and visualise flaws in the form of B-Scan cross-sectional view (front-view) of the pipe under test. In this paper, presents a custom-made perspex inspection head assembly integrated with a stand-alone, Li-ion battery-powered and IP67-grade water-immersible ultrasonic instrumentation and gauging system, which enables an efficient assessment of the condition and health of pipes in stringent environments. Extensive inspection was carried out on six samples of 12” Inner Diameter (ID) type carbon steel (CS) pipes with length of 500 mm and having machined wall thickness to simulate loss of wall-thicknesses from 10 % over a length 150 mm of pipe, using 5 MHz spherically focused transducers. Further inspection were carried out on a 12” CS pipe with four notches and four flat bottom holes (FBH) machined on the OD side. Identical flaws were also machined onto 12” CS pipe of total length of 700 mm containing water inside the pipe in flowing condition with water flow rate of 100 litres per minute (LPM). The test results demonstrate the effectiveness of the developed IP67 grade water-immersible ultrasonic pipe inspection and gauging instrumentation system for assessing the condition and health of long-length carbon steel pipes operating in harsh environments.

Publisher’s Note: “Battery-powered FPGA-based embedded system for ultrasonic pipe inspection and gauging systems” [Rev. Sci. Instrum. 94, 034712 (2023)

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Battery-powered FPGA-based embedded system for ultrasonic pipe inspection and gauging systems.

A water-immersible battery-powered field programmable gate array (FPGA)-based embedded system is a most suitable tool required to check the health of the pipe operating under harsh conditions. A novel, water-immersible, battery-powered, compact, stand-alone and FPGA-based embedded system has been designed and developed, which is suitable for ultrasonic pipe inspection and gauging systems useful for major applications in the petrochemical and nuclear industries. The developed FPGA-based embedded system is operated with lithium-ion batteries for more than five hours, and the IP67-grade system modules are capable of floating inside the pipe along with the flow of oil or water. Such applications require a system that is capable of acquiring large data under water-immersed conditions of battery-operated instrumentation. The onboard Double Data Rate (DDR) RAM of the FPGA module has been utilized for the storage of the 256 MBytes streams of A-scan data during evaluation for more than five hours. The experimentation of the battery-powered embedded system was carried out inside two samples of SS and MS pipes with the help of the in-house developed nylon inspection-head installed with two sets of spring-loaded eight Teflon balls and two 5MHz focused immersion transducers placed along the circumference at 180° apart. This paper provides brief details of the design, development, and evaluation phases of the battery-powered water-immersible embedded system suitable for ultrasonic pipe inspection and gauging, which can be expanded to 256 channels for demanding applications.

Design and development of water-immersible two-channel high-voltage spike pulser for under-water inspection and gauging of pipes.

A water-immersible two-channel high-voltage (HV) spike pulser has been designed, developed, and mounted inside the IP 67 (Ingress Protection 67) grade enclosure, and it is suitable for the ultrasonic Pipe Inspection and Gauging (PIG) system utilized in the petrochemical industry. Such a critical and strategic application requires a portable, miniaturized, and water-immersible water-tight pulser module, which resides inside the pipe carrying water or liquid petrochemicals. The developed spike pulser printed circuit board (PCB) generates a HV negative spike pulse up to -300V and 100ns half-amplitude pulse width, required for the energization of ultrasonic immersion transducers of 5-10MHz frequency. The water-immersible pulser is mounted inside the water-tight IP 67 grade enclosure, and it is operated through an external DC power supply/lithium batteries. The evaluation of the module was carried out using a two-channel water-immersible HV spike pulser, in-house developed preamplifier, and inspection head supported by four sets of spring-loaded Teflon balls for centering, and the inspection head carries two ultrasonic immersion transducers placed 180° apart and a sample SS pipe with a length of 400mm, Inner Diameter of 200mm, and Wall Thickness of 9mm. The two-channel pulser module was evaluated in water to measure the dimensions of the sample SS pipe. This two-channel water-immersible novel spike pulser has dedicated circuitry, and each channel is a standalone PCB and it operates through external LV and HV DC supplies. The module can be scaled up to 256 channels for dimension measurement and flaw detection of long length pipes. In the absence of any literature available on the water-immersible pulser for PIG systems, the present two-channel pulser module has been designed and developed, and the module was evaluated by gauging of the SS pipe from inside. This paper provides the details of the water-immersible HV spike pulser module suitable for the gauging of metallic pipes.

Superposition model of mode shapes composed of travelling torsional guided waves excited by multiple circular transducer arrays in pipes

In pipe inspection using ultrasonic guided wave technique, the current commercial transmitters are designed for the unidirectional guided wave excitation using multiple circular piezoelectric transducers arrays in the axial direction. However, the source with many individual transducer elements in arrays has difficulty in achieving an axisymmetric loading perfectly for defect detection. Therefore, a quasi-axisymmetric wave is formed due to many undesired wave modes are launched instead of a pure axisymmetric wave at a given excitation frequency. In this paper, a realistic superposition model of axial multiple transducer arrays is proposed. The model has many potential applications; one example is investigating the source influence on the generated quasi-axisymmetric wave effect. The analytical model is employed to achieve the predictions for investigating a transmitter’s influence for the unidirectional enhancement of torsional T(0,1) guided wave mode excitation in a pipe inspection system composing of three piezoelectric transducer ring arrays. The excitation function with variable power levels among transducers in arrays is also introduced. The predictive results using the analytical model for the distribution of circumferential displacement amplitudes over time are verified using the finite element method and a CLV-3D laser vibrometry measurement on a 219.1-mm-outer-diameter steel pipe without defect. A comparison between calculated and test results has been analysed quantitatively. The respective results are in good agreement. Thus, predictions for the superposed wavefield can be used to analyse the realistic characterisation of the excitation function in axial multiple transducer arrays. Additionally, a sensitivity analysis for part-circumferential crack detection using the quasi-axisymmetric torsional modes generated is also evaluated using finite element modelling.

A Hybrid Ultrasonic Guided Wave-Fiber Optic System for Flaw Detection in Pipe

The work presented in this paper shows that Fiber Bragg Grating (FBG) optical fiber sensors can potentially be used as receivers in a long-range guided wave torsional-mode pipe inspection system. Benefits over the conventional pulse-echo method arise due to reduced total travel distance of the ultrasonic guided wave reflections, since reflections from defects and structural features do not need to propagate a full round trip back to the transmitting collar. This is especially important in pipe configurations with high attenuation, such as coated and buried pipelines. The use of FBGs as receivers instead of conventional piezoelectric or magnetostrictive elements also significantly reduces cabling, since multiple FBG receivers can be placed along a single optical fiber which has a diameter on the order of only around 100 μm. The basic approach and sample results are presented in the paper. Additionally, a brief overview of some topics in ultrasonic guided waves is presented as a background to understand the inspection problem presented here.

On the probability of detecting wall thinning defects with dispersive circumferential guided waves

Two ultrasonic techniques are well established for pipe inspection and monitoring: highly sensitive ultrasonic spot thickness measurements, which can be presented in C-scan form, or low frequency guided waves that rapidly screen large areas for big defects. Recently there has been a growing interest in pipe inspection and monitoring systems exploring the middle ground between these two techniques by using higher frequency guided waves over shorter distances. In this paper the use of an axial transducer array (more suitable for monitoring applications) or a single axially scanned transducer (more suitable for inspections) that sends and receives dispersive circumferential guided waves around a pipe has been studied. The presence of a defect is detected as a result of a change in the wave travel time around the pipe circumference as a result of the thickness reduction. Both measurement modalities have a pitch between adjacent transducers/measurements. By approximating the pipe to a plate, a finite element model assisted method to evaluate the detection capabilities (probability of detection-POD) of this short range guided wave technique as a function of scan or transducer pitch is presented. The performance of three guided wave modes (A0, S0, and SH1) are compared in a 10mm thick plate. The results help to optimize the pitch and defect sensitivity of the setup. For the parameters investigated in this study, it was found that the S0 mode, at 2MHz.mm, is the most suitable for detecting wide shallow defects. For the same detection capabilities a much wider pitch can be used for S0 mode transducers as compared to SH1 mode transducers. Whereas the SH1 mode, at 3MHz.mm, is better suited to detecting narrow and deep defects using a relatively small pitch. The S0 mode is much less sensitive to these defects. The A0 mode was excluded from the POD analysis because it had a much higher variability in average thickness measurements, at comparable SNRs, compared to the other two modes.

Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide.

To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1) mode, L(0,1) mode, and L(0,2) mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1) mode, while the SH0-wave is easier to convert to the L(0,1) mode and L(0,2) mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide.

A New Guide Wave Inspection System Using Three Polarized Transverse Wave EMATs without Any Couplant

A guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to generate a guide wave using a piezoelectric element (PZT). However, the transverse wave-transducer using PZT needs to require a high viscosity couplant because the transverse wave cannot travel into typical liquid like water or oil. A guide wave inspection system that uses an electromagnetic ultrasonic transducer (EMAT) which does not require any couplant has then been developed to solve this trouble. First, a guide wave into a pipe, L, T and F-mode, can be transmitted and received by a polarized shear horizontal transverse wave propagating to the thickness direction when the vibration direction has been adjusted to the best direction. At next stage, the three EMATs for L, T and F-mode with different polarized vibration directions were piled up to improve the performance at the same position under the permanent magnet to inspect the pipe at the same condition. Next, the system with the EMATs can be confirmed to be able to detect three guide wave modes signal with enough intensity. Finally, the detection performance using the test pipes with any artificial defects has been done by the developed pipe inspection system, and any drilled holes and any notches can be detected. It is indicated that the developed system could be useful in real industrial field.

Pipe Inspection System by Guide Wave Using a Long Distance Waveguide

In the industrial fields, many high temperature structures that require a non-destructive inspection exist. However, there are currently few sensors that can carry out non-destructive testing in a high temperature environment. In particular, the ultrasonic sensor is normally not used at over 50 degrees Celsius. Also, a special sensor for high temperature is currently available, but there are various constraints; it has not yet reached a level that is useful in industry. Therefore, we have been developing a new sensor system using a long waveguide which can transmit an ultrasonic wave from a long distance. Especially, this study focuses on applying the developed technique to a pipe which is used in a nuclear power plant. Therefore, the best rectangular-shaped waveguide was studied and attempted to be wound around a pipe to be driven by an acoustic source of a guide wave. Finally, the L (0, 2) and T (0, 1)-mode guide waves were successfully detected by optimizing the shape of the opposite edge of the rectangular-shaped waveguide that could detect the reflected signal from an artificial defect machined into a test pipe.

Two-module robotic pipe inspection system with EMATs

This work introduces a two-module robotic pipe inspection system with ultrasonic NDE device to evaluate the integrity of pipe structures. The proposed robotic platform has high mobility. The two module mobile robot platform overcomes pipe obstacle structures such as elbow, or T-branch joints by cooperative maneuvers. Also, it can climb up the straight pipeline at a fast speed due to the wheel driven mechanism. For inspection of pipe structure, SH-waves generated by EMAT are applied with additional signal processing methods. A wavelet transform is implemented to extract a meaningful and specific signal from the superposed SH-wave signals. Intensity ratio which is normalized the defect signals intensity by the maximum intensity of directly transmitted signals in the wavelet transforms spectrum is applied to evaluate defects quantitatively. It is experimentally verified that the robotic ultrasonic inspection system with EMAT is capable of non-destructive inspection and evaluation of defects in pipe structure successfully by applying signal processing method based on wavelet transform.

Remote Devices for Inspection of Process Vessel and Conduits

Nuclear fuel reprocessing plants necessitate remote operations for the inspection of critical equipment. The monitoring of components is necessary in order to ensure that service-induced defects and abnormalities are detected and remedied at an early stage. The highly disordered nature of the workspace and the approach constraints, in nuclear plants give impetus to design and develop specialized equipment to achieve the objective. Working along these lines, this paper presents two developments for the in-service inspection (ISI) of internals of process vessel and pipes respectively. The ISI system for the dissolver vessel has been successfully demonstrated and the design for the pipe inspection system has been consolidated through simulations in a multi-body dynamics (MBD) tool and described herein.

Guided waves for NDT and permanently-installed monitoring

There is a gradual shift in emphasis from periodic inspection with detachable transducers (NDT) to permanently installed monitoring systems giving information about the structural integrity at preprogrammed intervals or on demand (SHM). The drivers of this change are discussed, together with the requirements of successful SHM systems. Particular issues are that NDT often involves scanning and this is not possible with typical SHM configurations; it therefore becomes important to cover a significant area of structure from each transducer position. Guided waves provide a possible solution to this problem and permanently installed guided wave pipe inspection systems are now available. The sensitivity obtained with a permanently installed system is significantly better than that in a one-off test as baseline subtraction can be employed. However, this is far from trivial as it is necessary to compensate for benign changes such as temperature. The guided wave technique does not provide accurate remaining thickness information and is best complemented by point measurements at selected locations. Another issue is that the SHM transducers must survive in operational conditions, which is particularly difficult at high temperatures. Recent work at Imperial College and associated spin-out companies on solutions to these problems is discussed.

An Approach to Pipe Image Interpretation Based Condition Assessment for Automatic Pipe Inspection

Condition assessment forms an important part of the asset management of buried pipelines. This is carried out through the use of inspection systems which usually consist of an image acquisition device attached to a mobile robotic platform. Complete or partial automation of image interpretation could increase the efficiency and objectivity of pipe inspection. A key component of an automatic pipe inspection system is the segmentation module. This paper describes an approach to automatic pipe inspection using pixel-based segmentation of colour images by support vector machine (SVM) coupled with morphological analysis of the principal component of the segmented image. The morphological analysis allows the principal component of the segmented image to be decomposed into the pipe flow lines region, the pipe joints, and adjoining defects. A simple approach to detecting pipe connections using fuzzy membership functions relating to defect size and location is also described.

Pipe Inspection System by Using Guided wave

Pipe Inspection System by Using Guided wave

実用化が始まった最新の非破壊検査技術 ガイド波による探傷監視システム

実用化が始まった最新の非破壊検査技術 ガイド波による探傷監視システム

On Circumferential Disposition of Pipe Defects by Long-Range Ultrasonic Guided Waves

Ultrasonic guided waves have been used extensively for long-range pipe inspections. The technique is based on detecting the guided wave echoes reflected from pipe defects located at a remote distance. The axial location of the defect from the transducer can be determined by the arrival time of the echo. However, further information about the defect, such as the circumferential size or distribution of the defect, is hard to obtain with conventional guided waves. This problem will be a critical issue for applications, such as discriminating the pipe corrosion defects from pipe welds. In this paper, a circumferential guided wave array is built for sending and receiving guided waves along the pipe. All of the elements are connected to a single channel pulser/receiver through multiplexers. An algorithm based on two-dimensional (2D) blind deconvolution is developed to process the guided wave echoes acquired by the multiplexed circumferential transducer array. The output of the algorithm can be utilized for evaluating the circumferential distributions and geometry of the defects. The processing algorithm is verified via both numerical simulations and experiments in the paper. This circumferential sizing algorithm can serve as an effective postanalysis tool for most available guided wave pipe inspection systems.

Mobile robots walk into the future

Describes some of the papers presented at an international colloquium on autonomous mobile systems held to celebrate 10 years of the Fraunhofer Institute for Factory Operation and Automation (IFF) in Magdeburg, Germany. Following definition of a mobile robot, papers on wheeled and biped robot platforms are discussed. These are followed by a review of some of the applications using dedicated robot systems, including an autonomous welding cell, a concept for process plant maintenance, a pipe inspection robot and systems for cleaning glass facades on high buildings. The latter work at IFF has resulted in two commercial systems, one already installed for the 1997 Leipzig Trade Fair and the other to be installed at the new Fraunhofer Foundation building in Munich in 2003.

Vector magnetometry and lightwave defect imaging sensor technologies for internal pipe inspection systems. Phase 1 and 2 feasibility study, conceptual design, and prototype development. Final report, March 1991–July 19913: Carroll, S.; Fowler, T.; Peters, E.; Power, W.; Reed, M. Little (Arthur D.) Inc., Cambridge Massachusetts (United States), PB94- 194198/GAR, 104pp. (5 Jan. 1994)

The Gas Research Institute (GRI) has been sponsoring the development of a vehicle and sensors for an integrated nondestructive internal inspection system for natural gas distribution pipes. Arthur D. Little has developed two sensor technologies, Vector Magnetometry (VM) and Lightwave Defect Imaging (LDI) for the system. The Vector Magnetometry sensor utilizes multiple arrays of miniature detection coils (fluxgate magnetometer elements); a three-axis array measures both the amplitude and phase of the magnetic leakage field that occurs in the vicinity of pipe wall defects. This technology is applicable to both cast iron and steel pipe.

Preservice inspection of BWR plants using advanced ISI system : Shouji, H.; Kobayashi, T.; Nagao, T. 12th International Conference on NDE in the Nuclear and Pressure Vessel Industries, Philadelphia, Pennsylvania (United States), 11–13 Oct. 1993. pp. 117–120. ASM International (1994) ISBN 0-87170-506-0

This paper reports experiences of preservice inspections using advanced Inservice Inspection (ISI) systems. The advanced ISI system consists of newly designed automated scanners, a high speed data acquisition/analysis station and automated pipe inspection system. This system has been developed to reduce examination time and radiation dose. The automated scanners are designed light weight and easy handling. A semi-automated inspection system has been used for pipe inspection. It is successful for taking reliable examination data, but not successful to reduce the radiation dose of personnel. For this reason, the automated pipe inspection system has been developed to replace the semi-automated system. The automated pipe inspection system consists of a small scanner, scanner controller and high speed personal computer for data acquisition. The data is analyzed by the data analysis station. The scanner has a light weight body in order to ease handling, and it requires almost the same clearance with manual examination. The PSI were successfully completed in a shorten time period. From this experience, the advanced ISI system will be very useful for ISI, especially reduction of radiation dose of personnel in future.